Changes in the Hierarchy of Functional Impairment From Middle Age to Older Age

Abstract

Background: Understanding the hierarchy of functional impairment in older adults has helped illuminate mechanisms of impairment and inform interventions, but little is known about whether hierarchies vary by age. We compared the pattern of new-onset impairments in activities of daily living (ADLs) and instrumental ADLs (IADLs) from middle age through older age.

Methods: We conducted a cohort study using nationally representative data from 32 486 individuals enrolled in the Health and Retirement Study. The outcomes were new-onset impairment in each ADL and IADL, defined as self-reported difficulty performing each task, assessed yearly for 9 years. We used multistate models and competing risks survival analysis to estimate the cumulative incidence of impairment in each task by age group (ages 50-64, 65-74, 75-84, and 85 or older).

Results: The pattern of incident ADL impairments differed by age group. Among individuals ages 50-64 and 65-74 who were independent at baseline, over 9 years' follow-up, difficulties dressing and transferring were the most common impairments to develop. In individuals ages 75-84 and 85 or older who were independent at baseline, difficulties bathing, dressing, and walking were most common. For IADLs, the pattern of impairments was similar across age groups; difficulty shopping was most common followed by difficulty managing money and preparing meals. Complementary analyses demonstrated a similar pattern.

Conclusions: These findings suggest that the hierarchy of ADL impairment differs by age. These findings have implications for the development of age-specific interventions to prevent or delay functional impairment.

Keywords: Activities of daily living; Functional impairment; Middle-aged.

Figure 1.

Cumulative incidence of ADL impairments by age group. ADL indicates activities of daily living. The figure shows the cumulative incidence of new ADL impairments at 9 years with 95% confidence intervals for each age group (ie, 50–64 years, 65–74 years, 75–84 years, and 85 years or older). Cumulative incidences were determined using multistate modeling and competing risk survival analysis to account for the competing risk of death. Analyses incorporated survey weights, strata, and clusters to account for the complex Health and Retirement Study (HRS) survey design.

Figure 2.

Cumulative incidence of IADL impairments by age group. IADL indicates instrumental activities of daily living. The figure shows the cumulative incidence of new IADL impairments at 9 years with 95% confidence intervals for each age group (ie, 50–64 years, 65–74 years, 75–84 years, and 85 years or older). Cumulative incidences were determined using multistate modeling and competing risk survival analysis to account for the competing risk of death. Analyses incorporated survey weights, strata, and clusters to account for the complex Health and Retirement Study (HRS) survey design.

Figure 3.

Order in which incident difficulty dressing, transferring, and bathing developed by age group. The figure shows the order in which incidence difficulty dressing, transferring, and bathing developed by age group (ie, 50–64 years, 65–74 years, 75–84 years, and 85 years or older) among individuals who were independent in these activities of daily living (ADLs) at baseline. The figure shows the proportion of individuals with each of the listed outcomes, which were the most common incident impairments observed in the cohort. Proportions were determined by counting new-onset ADL impairments over follow-up. Analyses incorporated survey weights, strata, and clusters to account for the complex Health and Retirement Study (HRS) survey design.